Date: Fri, 22 Jul 2016 09:52:04 -0500 From: Pedro Giffuni <pfg@FreeBSD.org> To: Bruce Evans <brde@optusnet.com.au>, Alexey Dokuchaev <danfe@freebsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r303146 - head/usr.bin/sed Message-ID: <dee9732d-5cd6-6440-ad53-7fb184df7a71@FreeBSD.org> In-Reply-To: <20160722165435.C2805@besplex.bde.org> References: <201607211417.u6LEHaPR086378@repo.freebsd.org> <20160722043536.GB37437@FreeBSD.org> <20160722165435.C2805@besplex.bde.org>
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On 07/22/16 02:13, Bruce Evans wrote:
> On Fri, 22 Jul 2016, Alexey Dokuchaev wrote:
>
>>> Log:
>>> sed(1): Appease older GCC.
>
> "Appease" actually seems to be the correct wording here since gcc's
> detection
> of a variable that might be used unitialized seems to report one that is
> not used uninitialized.
>
>> Isn't it also being dictated by style(9) and common sense? :)
>
> You missed that this combines a style fix in previous gcc appeasement
> (or just excessive paranoia) in one variable with appeasement for
> another variable, since copying the previous appeasement would copy
> its style bug. The 2 variables are used in exactly the same limited
> way.
>
Yes, the first one is just a style fix while I was there.
The oldpsanl bogusness was breaking the build with gcc42. gcc48+, clang
and coverity all agree it was a false positive.
It was likely a side effect of raising the WARNS level to 5.
>>> Modified:
>>> head/usr.bin/sed/process.c
>>>
>>> @@ -97,11 +97,12 @@ process(void)
>>> {
>>> struct s_command *cp;
>>> SPACE tspace;
>>> - size_t oldpsl = 0;
>>> + size_t oldpsl;
>>> char *p;
>>> int oldpsanl;
>>>
>>> p = NULL;
>>> + oldpsanl = oldpsl = 0;
>
> Multiple assignments on a single line is not very good style and is
> probably
> not KNF. Here it is further from being good style since the variables
> have different types. Since both types are integral and the value is 0
> the implicit type conversions don't change the value. However, compilers
> should warn about down-converting a size_t to an int unless they do the
> analysis that this is safe because the value in the size_t is known to
> fit in the int.
>
Doing the multiple assignment seemed natural and readable as both are
(perhaps equally bogus) initializations.
I did notice the different types after committing. Perhaps swapping the
assignment would have been preferable? I suspect the compiler manages to
optimize out the casting.
Pedro.
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